It could be the pump motor or the pump causing too much draw.
To check the motor, turn off power to the pump motor. Mark the 3 wire legs coming from the big blue VFD to the motor. Mark tham leg 1, leg 2, and leg 3.Take a picture with your phone to use to put them back in the correct spots.Remove the 3 legs going to the motor from the bottom of the VFD. Then using a multi meter set to ohms check the ohms between leg 1 & 2, then leg 1 & 3, then leg 2 & 3. You should get the same reading each time. If one reading is significantly different from the other 2 then the motor needs to be replaced. If they are all the same then the motor is probably okay. It's possible that it could still be the motor, but further diagnostics require a megger. Reinstall the 3 legs of the motor back to the VFD in the same spots. Turn the power back on to the pump motor.
It's also possible that the pump could be the problem or that some of the nozzles are clogged causing too much pressure on the pump. Usually though you would get a fault code on the VFD with a motor or pump problem causing too much draw.
Good luck, the G5s is my least favorite car wash to work on. They are hard to diagnose and to access, but they do a good job of cleaning.